add a style for kbd elements

Author: dwwoelfel

src/App.css

@@ -65,3 +65,17 @@ blockquote {
 li p {
   margin: 0;
 }
+
+kbd {
+  font-size: calc(1rem - 6px);
+  line-height: 1rem;
+  display: inline-block;
+  padding: 2px 5px;
+  color: #444d56;
+  vertical-align: middle;
+  background-color: #fafbfc;
+  border-bottom-color: #d1d5da;
+  border: 1px solid #d1d5da;
+  border-radius: 6px;
+  box-shadow: inset 0 -1px 0 #d1d5da;
+}